II.

Properties and Occurrence

British chemists Sir William Ramsay and Morris Travers first separated neon from other noble gases in 1898. Neon and the other noble gases do not normally form compounds with other elements. During the past few decades chemists have managed to induce several of the noble gases to form compounds with other extremely reactive elements, such as fluorine, but neon and helium have so far resisted these efforts. Neon melts at -248.59°C (-415.46°F), boils at -246.08°C (-410.94°F), and has a density of 0.8999 g/l at 0°C (32°F). The atomic weight of neon is 20.18.

Stars much more massive than the Sun produce neon during the later stages of nuclear fusion. The abundance of neon on Earth is lower than in the universe generally. Neon constitutes just 15 parts per million in the atmosphere. (see Star: How Stars Produce Energy)

Neon is obtained for commercial purposes from air by the process of fractional distillation. In this process, air is cooled until it liquefies, and then it is gradually allowed to warm. The tiny fraction of the air that boils off at -246.08°C is neon, which is then collected. Some minerals also contain tiny amounts of trapped neon gas.

Neon occurs naturally as three stable isotopes. These isotopes are neon-20, which is the most abundant isotope; neon-22; and neon-21. All isotopes of an element have the same number of protons in their nuclei but have differing numbers of neutrons. The first demonstration of the existence of multiple stable isotopes of a single element was performed with neon in 1912.